CN202524299U

CN202524299U - Primary edge control type switch power supply with high-precision constant-voltage/constant-current output and high-pulse-frequency (PF) value

Info

Publication number: CN202524299U
Application number: CN2012201277111U
Authority: CN
Inventors: 张小平
Original assignee: JIANGSU SENCHIP MICROELECTRONICS CO Ltd
Current assignee: JIANGSU SENCHIP MICROELECTRONICS CO Ltd
Priority date: 2012-03-30
Filing date: 2012-03-30
Publication date: 2012-11-07
Anticipated expiration: 2022-03-30

Abstract

The utility model discloses a primary edge control type switch power supply with high-precision constant-voltage/constant-current output and a high-pulse-frequency (PF) value. The primary edge control type switch power supply comprises an electromagnetic interference and filtering circuit, a rectifying filtering circuit, a transformer, a voltage stabilizing buffer circuit, a filtering shaping output circuit, a metal oxide semiconductor (MOS) tube, a sampling resistor and a constant-voltage and constant-current pulse frequency control (PFC) driving module, wherein the voltage stabilizing buffer circuit, the filtering shaping output circuit, the MOS tube, the sampling resistor and the constant-voltage and constant-current PFC driving module are connected in parallel with the transformer. Due to the adoption of the primary edge control type switch power supply, the transformer primary edge is detected and is fed back to a PFC control chip. A pulse frequency modulation (PFM) mode is adopted, so that a high-precision current and a high-precision voltage can be output. Compared with a traditional driving circuit, peripheral devices such as optical couplers and the like are omitted, so that a peripheral circuit is simpler. The PF value and the electric work efficiency of the whole power supply are obviously improved. The primary edge control type switch power supply has the obvious characteristics of simple periphery circuit, low cost and high performance, which is suitable for large-scale popularization and application.

Description

Former limit control type Switching Power Supply with high accuracy constant voltage/constant current output and high PF value

Technical field

The utility model belongs to field of switch power, and relating to a kind of tool high accuracy has constant voltage/constant current output, and the Switching Power Supply of the former limit control technology of high PF value.

Background technology

Traditional Switching Power Supply usually in Switching Power Supply for voltage, the electric current that guarantees to export reaches a higher precision, generally be employed in an output termination optocoupler, through optocoupler output end voltage is fed back to input; Input is being regulated output voltage according to feedback signal; Such circuit makes that the structure of circuit is comparatively complicated, needs a large amount of components and parts, and the voltage of output, the precision of electric current are relatively poor; And there is aging problem in optocoupler; The stability and the life-span that are circuit all receive certain influence, and this kind way makes that also production cost is higher, and PF value, electric work efficient are very low.

Summary of the invention

It is simple that the purpose of the utility model provides a kind of peripheral circuit, and can export the demand that high-precision voltage, electric current satisfy the LED lamp, has higher PF value and efficient simultaneously, realizes low-cost and high performance drive circuit.

The utility model solves the technical scheme that its technical problem adopted: a kind of former limit control type Switching Power Supply with high accuracy constant voltage/constant current output and high PF value; Comprise electromagnetic interference, filter circuit; Current rectifying and wave filtering circuit; Transformer also comprises voltage stabilizing buffer circuit, filter shape output circuit, metal-oxide-semiconductor and sampling resistor, constant pressure and flow PFC control and driving module with transformers connected in parallel.

As improvement, said constant pressure and flow PFC control and driving module adopts the PFC control chip; Eliminate the civil power of electromagnetic interference, filter shape through electromagnetic interference, filter circuit and after current rectifying and wave filtering circuit is transported to the transformer transformation, export to the output of filter shape output circuit, the former limit of said transformer and sampling resistor RS feed back signal to voltage, the electric current of PFC control and driver module control metal-oxide-semiconductor switching frequency adjusting output.

As further improvement, the model that said constant pressure and flow PFC chip adopts is SD6857, and modulating mode is PFM.

As further improvement, said voltage stabilizing buffer circuit is the former limit at transformer, and Pri-end resistance R 5 N that 3 parallel connections are connected diode D1 then with capacitor C holds, then the P termination Pri+ of diode; Simultaneously voltage-stabiliser tube ZD1 and resistance R 5, capacitor C 3 are parallelly connected, and its P termination Pri-, N end hold with the N of the D1 of diode and be connected; Be serially connected with Ultrafast recovery diode D4 between the cathode output end of said filter shape output circuit and the negative input, connect with capacitor C 8 after resistance R 19, the R20 parallel connection, parallelly connected with diode D4 then, then with electric capacity, C9, C10, resistance R 21 parallel connections.

Adopt technique scheme; Make and the utlity model has following advantage: feed back to PFC constant pressure and flow control chip through detecting the former limit of transformer; Adopt the modulation system of PFM, the switching frequency of controlling metal-oxide-semiconductor through built-in logic controller reaches output high accuracy and voltage and current; The integrated function of PFC has higher PF value; Adopt the modulation system of PFM, made it possible to the very high-precision electric current and voltage of output, had higher electric work efficient simultaneously; Be provided with a voltage stabilizing buffer network on the former limit of transformer, make it possible to reduce the impact of input voltage, a comparatively stable power is provided to chip to circuit.

Description of drawings

Below in conjunction with accompanying drawing the utility model is done further explain:

Fig. 1 is the circuit block diagram of the utility model;

Fig. 2 is the circuit theory diagrams of the utility model.

Embodiment

Shown in Fig. 1～2, the utility model mainly comprises electromagnetic interference, filter circuit, current rectifying and wave filtering circuit, and transformer reaches the voltage stabilizing buffer circuit with transformers connected in parallel, filter shape output circuit, metal-oxide-semiconductor and sampling resistor, constant pressure and flow PFC control and driving module.Electromagnetic interference, filter circuit adopt inductance L 1 and resistance R 1 parallel connection to be serially connected in one side of input power cord then; Inductance L 2, R2 parallel connection are serially connected in the another side of power input line; Then with capacitor C 1 parallel connection; Protective tube F1 of serial connection before electromagnetic interference, filter circuit in the time of can being used for preventing that circuit is unstable, producing a bigger electric current and the utility model is caused damage.Wherein: current rectifying and wave filtering circuit adopts rectifier bridge B1, electrochemical capacitor C2, the V+ of electrochemical capacitor C2 and rectifier bridge B1, V-parallel connection; Make the alternating current of access become level and smooth direct current through current rectifying and wave filtering circuit; Voltage stabilizing, the described voltage stabilizing buffer network of buffer network are the former limit at transformer, and Pri-end resistance R 5 N that 3 parallel connections are connected diode D1 then with capacitor C holds, then the P termination Pri+ of diode; Simultaneously voltage-stabiliser tube ZD1 and resistance R 5, capacitor C 3 are parallelly connected, and its P termination Pri-, N end hold with the N of the D1 of diode and be connected, and can effectively suppress the infringement that circuit is caused owing to the input voltage shakiness; Feed back to PFC constant pressure and flow control chip through detecting the former limit of transformer, adopt the modulation system of PFM, the switching frequency of controlling metal-oxide-semiconductor through built-in logic controller reaches output high accuracy and voltage and current; Adopt the modulation system of a kind of high efficiency PFM (pluse frequency modulation, pulse frequency modulated), made it possible to export the electric current and voltage of degree of precision, had higher electric work efficient simultaneously.

The chip that the utility model adopts is SD6857, pin one Vac, and function is: the ac input voltage waveform sampling, pin two Vavg, function is: ac input voltage mean value; Pin 3FB, function is: detection feedback; Pin 4Vcc, function is: the chip power supply end; Pin 5GND, function is: the chip grounding leg; Pin 6CS, function is: the current sample pin; Pin 7DR, function is: the gate driving pin; Pin 8NC, function is: empty pin; Resistance R 16, R15, R14 series connection, the V+ of R16 one termination rectifier bridge B1, another termination R15; R15 one termination R16, the other end is taken over pin 1Vac; Resistance R 14, one termination pin 1Vac, other end ground connection; Capacitor C 6, one end ground connection, the other end is taken over pin 1Vac; Resistance R 16, R17, R18 series connection, the V+ of R16 one termination rectifier bridge B1, another termination R17; R17 one termination R16, the other end is taken over pin 2Vavg; Resistance R 18, one termination pin 2Vavg, other end ground connection; Capacitor C 7, one end ground connection, the other end is taken over pin 2Vavg; Resistance R 7, R13 series connection, the ancillary coil Aux+ of resistance R 7 one termination transformer T1, the other end is taken over pin 3FB; R13 one termination pin 3FB, other end ground connection; Resistance R 3, R4 series connection, the V+ of resistance R 3 one termination rectifier bridge B1, other end connecting resistance R4; Resistance R 4 one terminating resistor R3, the other end is taken over pin 4Vcc; Diode D2, resistance R 6 series connection, the Aux+ of the P termination transformer T1 ancillary coil of diode D2, the N terminating resistor R6 of D2; The N end of one terminating diode D2 of resistance R 6, the other end is taken over pin 4Vcc; Capacitor C 5 one termination pin 4Vcc, other end ground connection; Pin 5GND ground connection; Resistance R 8, R9 parallel connection, an end ground connection, the S end of other end connecting resistance R12 and MSE pipe; Resistance R 12, one termination parallel resistor R8, R9, the other end is taken over pin 6CS; Resistance R 11, parallelly connected with diode D3, the G end of the P termination metal-oxide-semiconductor Q1 of diode, N termination pin 7DR; Pin 8NC, unsettled; The Pri+ on the former limit of the D termination transformer T1 of metal-oxide-semiconductor, G terminate at the P end of resistance R 11 and diode D3 parallel connection, and capacitor C 4 one terminates at the S end of metal-oxide-semiconductor, and another side is connected on the D end of metal-oxide-semiconductor Q1, and resistance R 10, terminates at the G end of metal-oxide-semiconductor Q1, an end ground connection.

Start-up course: after the voltage of input is set up, at first give capacitor C 5 chargings by starting resistance R3, R4, the voltage of C5 raises gradually, when reaching the starting resistor threshold value of chip SD6857; Chip SD6857 starts working, and driving pulse is provided then, by the output of pin 7DR end, opens metal-oxide-semiconductor; The electric current on the former limit of transformer begins to increase, when surpassing current limit value, circuit protection, output shutoff; Starting resistance R3, R4 can not provide enough voltage at this moment, so capacitor C 5 discharges, and capacitance voltage descends gradually, and ancillary coil passes through to supply power to chip SD6857 after diode D2, resistance R 6 rectifications simultaneously; Keep the operate as normal of chip SD6857, output is turn-offed, and the voltage on former limit, electric current begin to descend; Behind the unlocking condition that satisfies the control of constant pressure and flow loop, chip SD6857 is opening M OS pipe Q1 again, so goes round and begins again.Peak current detection: when the metal-oxide-semiconductor conducting, this moment, the FB terminal voltage was negative, and sampling resistor, R8, R9, R12 detect primary current and be linear increase, when surpassing peak current, chip SD6857 shutoff metal-oxide-semiconductor Q1; Feedback voltage detects: when metal-oxide-semiconductor Q1 turn-offs; This moment, the FB terminal voltage was for just; Sample for whole lamp 2/3 time point at FB voltage; The voltage that obtains of sampling through amplification, keep, relatively be used for control the constant voltage loop dead time Tcv. circuit simultaneously to FB voltage for just, calculate for the time of negative or attenuated oscillation, FB is that the positive time is Toff1, the indication transformer ancillary coil has electric current to flow through; FB is Toff2 for negative time T on, the time of FB attenuated oscillation, does not have electric current to flow through at the ancillary coil of this two time transformer T1.Under the constant condition of peak current,, need to keep Toff1=Toff2+Ton for reaching the purpose of output constant current.The constant current loop is exactly the high and low comment time of utilizing the FB that is detected, confirms the dead time Tcc of constant current loop, keeps output current constant thereby reach control; PF proofreaies and correct: PFC function that chip is integrated; Adopt the average voltage control method, through pin Vac, peripheral circuit detect the voltage on former limit, be reference current with the product of the detected value of output voltage error amplifying signal and commutating voltage; Be added to the current error amplifier in current feedback; Regulate input current average value through error amplifier, make input current and voltage homophase, and near sinusoidal waveform.Input current and reference current relatively after; Its high fdrequency component averages out processing, and average current error signal and sawtooth waveforms relatively back form the PFM signal of controlling metal-oxide-semiconductor Q1 break-make, obtain a higher PF value; The voltage on the former limit of peripheral circuit electric circuit inspection through pin Vavg; Obtain a comparatively constant input voltage, make at input voltage when bigger fluctuation occurring, still can guarantee to export a comparatively constant voltage, electric current; Guarantee a higher PF value, bigger fluctuation can not occur.Adopted the modulation system of a kind of high efficiency PFM (pluse frequency modulation, pulse frequency modulated), in conjunction with low the having a few and PWM (pluse width modulation of PFM circuit power consumption; Pulse width modulation) advantage done of delivery efficiency makes it possible to a higher efficient, the filter shape output circuit; Between the anode of the Sec+ of the secondary coil of transformer T1 end and output, meet a Ultrafast recovery diode D4, the P termination Sec+ of D4, the anode of the N termination output of D4; Resistance R 19, R20 parallel connection; Connect with capacitor C 1 then, parallelly connected with diode D4 then, parallelly connected with capacitor C 9, C10, resistance R 21 again; Constituted a filtering shaping circuit, can comparatively level and smooth, a less out-put supply of fluctuation be provided for load.

Though it is pointed out that the foregoing description to the utility model detailed text description of contrasting, these text descriptions are just to the simple description of the utility model mentality of designing, rather than to the restriction of the utility model thinking.Any combination, increase or modification that is no more than the utility model mentality of designing all falls in the protection range of the utility model.

Claims

1. former limit control type Switching Power Supply with the output of high accuracy constant voltage/constant current and high PF value; Comprise electromagnetic interference, filter circuit; Current rectifying and wave filtering circuit; Transformer is characterized in that also comprising voltage stabilizing buffer circuit, filter shape output circuit, metal-oxide-semiconductor and sampling resistor, constant pressure and flow PFC control and driving module with transformers connected in parallel.

2. the former limit control type Switching Power Supply with high accuracy constant voltage/constant current output and high PF value according to claim 1 is characterized in that said constant pressure and flow PFC control and driving module adopts the PFC control chip; Eliminate the civil power of electromagnetic interference, filter shape through electromagnetic interference, filter circuit and after current rectifying and wave filtering circuit is transported to the transformer transformation, export to the output of filter shape output circuit, the former limit of said transformer and sampling resistor RS feed back signal to voltage, the electric current of PFC control and driver module control metal-oxide-semiconductor switching frequency adjusting output.

3. the former limit control type Switching Power Supply with high accuracy constant voltage/constant current output and high PF value according to claim 2 is characterized in that the model that described constant pressure and flow PFC chip adopts is SD6857, and modulating mode is PFM.

4. the former limit control type Switching Power Supply with high accuracy constant voltage/constant current output and high PF value according to claim 1; It is characterized in that: said voltage stabilizing buffer circuit is the former limit at transformer; Pri-end resistance R 5 N that 3 parallel connections are connected diode D1 then with capacitor C holds, then the P termination Pri+ of diode; Simultaneously voltage-stabiliser tube ZD1 and resistance R 5, capacitor C 3 are parallelly connected, and its P termination Pri-, N end hold with the N of the D1 of diode and be connected.

5. the former limit control type Switching Power Supply with high accuracy constant voltage/constant current output and high PF value according to claim 1; It is characterized in that: be serially connected with Ultrafast recovery diode D4 between the cathode output end of said filter shape output circuit and the negative input; Connect with capacitor C 8 after resistance R 19, the R20 parallel connection; Parallelly connected with diode D4 then, then with electric capacity, C9, C10, resistance R 21 parallel connections.